A large body of research suggests that minor delinquency is often a precursor to substance use, and that initiation of both behaviors often occurs as children are experiencing other difficult life transitions. Evidence of a reciprocal relationship between delinquency and substance use has led researchers to hypothesize a set of shared underlying causes, which may include cognitive and self-control deficits and in some cases mental health problems as well. This research raises the possibility that interventions that target either delinquency or substance use (or underlying shared causes) may help prevent the persistence or escalation of both behaviors. Unfortunately the most vulnerable youth in our society are also disproportionately likely to be disconnected from key social systems. This suggests that a particularly important delivery context for selective prevention interventions may be the juvenile justice system. We request funding to implement and pilot-test an integrated cognitive behavioral therapy (CBT) program that is widely used in juvenile correctional settings but has not yet been adapted for delivery or tested for use with juvenile offender populations in the community setting. A community-based CBT program, which would be relevant for a much larger juvenile offender population compared to a program delivered in detention, must address additional challenges that are less pressing within the detention setting, such as ensuring sustained program participation and contending with outside community influences on youth attitudes and outcomes. Our proposed project is made possible by a unique collaboration between our interdisciplinary University of Chicago-based research team and the Juvenile Probation and Court Services Department of the Circuit Court of Cook County. The targeted population is the large group of youth 13-17 years of age who are under the supervision of Juvenile Probation. The proposed study utilizes a two-phase design: (1) a pre-randomized development phase that involves a small group feasibility study to adapt the CBT intervention model for the community probation setting; and (2) the pilot randomized clinical trial (RCT) of efficacy. The RCT will randomly assign youths who are under probation supervision to: (a) status quo probation services (N=100); (b) a 12-week group CBT intervention for at-risk youth (CBT-ARY) (N=100); or (c) a combined intervention that supplements CBT with attendance reinforcers to (CBT-ARY+) encourage program participation (N=100). Primary outcome measures will focus on proximal goals of intervention, including cognitive processes, attitudes, and mental health. Distal outcomes of substance use, aggression, other forms of violent or criminal behavior, and recidivism rates will be also be measured. Results from the two phases will guide a future application for a full-scale effectiveness trial.